I've been backpacking for over 30 years, all over California, Minnesota, and many western states. I hike year-round in all weather, and average 500+ miles (800+ km) per year. I make a point of using lightweight gear, and smaller volume packs. Doubting I can ever be truly ultralight, I try to be as light as I can yet still be comfortable. I start early and hike hard so as to enjoy the afternoons exploring/chilling. I usually take a freestanding tent and enjoy hot evening meals. If not hiking solo I am usually with my brother-in-law Dave or my twin children.

Winter backpacking brings plenty of frustration to what, in milder conditions, are mundane tasks. Sleeping pad inflation is one chore that I have always disliked as I was not happy with the choices available to get air into my pads without blowing them up by mouth (which introduces moisture inside them). The multi-function Therm-a-Rest Pump Sack will not only inflate my pads quickly, it also protects my gear and can ease my sore rump. How? Please read on.

Product Description

The Therm-a-Rest NeoAir Pump Sack (hereafter referred to as the Pump Sack) is a very interesting piece of gear. It is about the size of a sleeping bag storage sack but instead of cotton it is made of waterproof 70 denier ripstop nylon. This bright sack is what the company calls Daybreak Orange (but what I always think of as MSR orange having owned many tents of this color over the years).

Just like a storage sack the top of the Pump Sack has a draw-cord running around the edge that secures with a spring-loaded cord-lock. At the bottom is a black-edged grab handle, useful for carrying the Pump Sack if it is full of something. (Below is a shot of the Pump Sack with the handle showing.) But underneath this handle, and being protected by it, is the star of the show, the valve-inflation plug.

The plug is a disk of flexible clear urethane-type material that is chemically welded to the nylon of the Pump Sack. It is pushed over the inflation valve of a sleeping pad, stretching as it does so. The pressure from stretching and the inherent stickiness of the urethane keep it place. Above is a shot of the plug in the proper position on a NeoAir All-Season pad.

Once plugged onto the valve the Pump Sack is grabbed by the top and shaken to open the sack fully. The top is then closed, either by pulling the draw-cord quickly or, as I do, just pinching it and rolling down like closing a dry-sack. By rolling the Pump Sack down towards the bottom, air is forced from the Pump Sack into the pad. Therm-a-Rest says that a regular sized NeoAir mattress can be filled with just over two bags of air. Once I got the hang of it I was hitting that mark myself. A full three can most times even fill my Large size pads, but sometimes a partial fourth is needed.

The company suggests that the Pump Sack is useful for other things as well, one of which being a water-proof backpack liner. Here is a picture of it in my Osprey Exos 34 while packing for a hike.

The company also suggests that the Pump Sack may be used as a stool by inserting a partially inflated NeoAir pad inside it rolled up on its end and then closing the sack. The resulting cylinder is used upright so that the NeoAir's tubes are running vertically.

Field Locations

These are some of the backpacking and camping trips I have used the NeoAir Pump Sack during the fall of 2011, all in the state of Minnesota.

One trip saw me driving and day-hiking all over Chippewa National and Paul Bunyan State Forests as I pre-scouted locations for this winter's snow-packing trips. I stayed on Hungry Man Lake. The low was in the upper 20's F ( -2 C) when I went to bed, but warmed up to almost 40 F (4 C) in the middle of the night when it started raining.

Next was an overnighter on the North Country Trail where I stayed at the official NCT campsite on the north side of Waboose Lake. The low was right at freezing. The picture below was from this trip.

I used it on a three-day 34 mi (55 km) loop backpacking trip on the North Country Trail and Woodtick Trail south of Leech Lake in Chippewa National Forest. The first night saw sleet and a low of 19 F (-7 C) and the next was 24 F (-4 C).

Last was another pre-scouting trip was up and down the Red River of the North verifying that canoeists' primitive river camp sites would work for sled-packing trips this winter. I camped at Buffalo River State Park.

Observations

I have been heavy into winter backpacking since 2003. One of the biggest problems with it is finding a way to easily inflate my sleeping pads that will keep moisture from my breath from being introduced to the inside of the pad where it will freeze, compromising the r-value and adding weight. After spending many years trying many different inflation devices I finally found a good one last winter and honestly never expected to try anything else. Little did I know that I would end up with not one but two new inflation devices this year. This is the story of one of them.

I have had many types of pump-sacks for winter pads. Just about every pad I have owned that is made for cold temps came with one, or is an option available for separate purchase. At the high end of the scale they have just been OK, working to inflate but quite slow and frustrating to use. At the other end have been some that are downright maddening, barely moving air. All are just too dang small in my opinion. With the Pump Sack Therm-a-Rest gets the size right.

Once I practiced a couple times at home I had no problem getting fast fills with the Pump Sack. The only trouble I have is the plug popping off from too much movement while inflating my pad. This too got better with practice/use.

Therm-a-Rest suggests that the Pump Sack can be used as a pack liner. I did not give this much thought when I first got it, but wished I had brought it along when I joined my brother-in-law for a section hike on the Pacific Crest Trail, including two days of wet hiking in Washington and Oregon that saw my pack cover totally fail, getting my gear wet, much to my dismay. Right after getting back I had a trip planned and needed the same pack/cover combo but had not had time to re-treat the DWR on the pack cover. Remembering the suggestion I used the Pump Sack as a liner, the first time I have ever used a pack liner. The trip did see rain, but my gear stayed nice and dry. Thanks Pump Sack.

With the same idea in mind I used it as a waterproof sack to keep my clothes, camera, and phone dry in a camp at Hungry Man Lake. I had decided to relive my tent-less teens, when I used to sleep on picnic tables anytime I had one available. As the forecast was "rain tonight" I wanted to make sure my stuff was protected if it came. The Pump Sack did a good job, as the skies did dump on me in the early morning hours. Here is a shot taken late at night before I had to run for the waiting tent. (I had to blur the bag as it is a preproduction design I am helping with.)

While Therm-a-Rest says that the Pump Sack may be used as a seat I never tried this for a couple of reasons. First I did not like the idea of the 70d nylon being the only thing between my precious NeoAir and a possible burr on the ground. (Burdock is horrible here in the fall.) Second I was already using a Jembe Seat kit (see review) which does the same thing but uses much burlier material.

But hey! Two out of three ain't bad. I envision using the Pump Sack in the future on hikes that I expect a lot of rain, to take advantage of its dual nature. I leave with a picture of it being used on the Woodtick Trail.

Product tested and reviewed in each Formal Test Report has been provided free of charge by the manufacturer to BackpackGearTest.org. Upon completion of the Test Series the writer is permitted to keep the product. Owner Reviews are based on product owned by the reviewer personally unless otherwise noted.